Cooked flavors for smoking products

ABSTRACT

Reducing sugars are reacted with ammonium hydroxide or ammonium salts in the presence of a trace amount of certain amino acids to produce reaction flavors for use in smoking compositions and particularly those having a high content of tobacco stems.

BACKGROUND OF THE INVENTION

The present invention relates to reaction flavors, and more specificallyto cooked flavors suitable for use in smoking compositions. Theinvention is also concerned with processes for preparing reactionflavors and incorporating them into smoking compositions, particularlythose having a high content of tobacco stems, to produce a moreacceptable and flavorful smoking product.

In general, tobacco stems and midribs represent an unsatisfactoryportion of the cured tobacco leaf, from the standpoint of smoking, inthe sense that they produce a stemmy taste on smoking and lack thedesirable aroma and taste generally associated with tobacco lamina.

Stems are usually separated from the desirable leaf or lamina oftobacco. To throw away the stems and midribs is uneconomical and, forthis reason, methods have been devised to modify and make them usable insmoking products. One of the methods which has been found to berelatively satisfactory, because of its simplicity and low cost, is topass the stems between rollers in order to break up the bulky, rigidstructure and to produce rolled stems, which are a flattened, loosenedproduct which can be shredded and blended with shredded tobacco leaf.

It has been found, however, that the rolled stems still impart a certainamount of the harshness and off-taste which are imparted by tobaccostems to the smoke from cigarettes or other tobacco products into whichthey are introduced. Stems from burley tobacco are particularlyundesirable in this respect. As a consequence, only a small portion ofthe stems from tobacco used in filler for cigarettes or cigars can berolled and blended back into the filler.

We have now discovered a means by which rolled stems may be used toproduce tobacco products having a more acceptable smoke. Stems from bothbright and burley tobacco treated by our process may be used in greaterproportion to produce a cigarette which yields comparatively blandsmoke.

The present invention comprises contacting tobacco stems, either before,during or after passing the stems between rollers, with a solution of areaction flavor product produced by reacting reducing sugars with asource of ammonia in the presence of trace amounts of amino acids.

The reaction of sugars with ammino acids to produce desirable flavorantsfor smoking materials has generated increased interest. For example,U.S. Pat. No. 3,478,015 describes "browning reactions" in which an aminoacid and a sugar having an active carbonyl are reacted in a lower alkylpolyhydric alcohol solvent in the absence of water at a temperature lessthan 90° C. for about 5 to 15 hours. Generally the amino acid to solventratio is in the range of 1 to 3% by weight and the sugar to solventratio is in the range of 3 to 15% by weight. The reaction is carried outin such a manner that no free amino acid remains in the final product.The resultant reaction mixture is applied to tobacco to about 1% byweight of the tobacco.

U.S. Pat. No. 3,920,026 describes tobacco flavorants prepared byreacting valine with a carbonyl compound selected from sugars, dihydroxyacetone, or pyruvaldehyde. The molar ratio of amino acid to carbonylcompound can be from about 1:0.5-10, with a ratio of 1:4-5 beingoptimum. The reaction takes place in a solvent such as glycerol orpropylene glycol and at a temperature between about 120° and 200° C.,and preferably at about 150° to 160° C. for 0.5 to 5 hours depending onthe type of sugar used. Flavanoid catalysts, such as quercetin or rutinor a hydroxyacid such as ascorbic acid, may be used. The reactionmixture may be applied directly onto tobacco or may be fractionated toseparate the volatile and nonvolatile fractions, which are then used astobacco flavorants.

U.S. Pat. No. 3,722,516 discloses the addition of dihydroxyacetone aloneor in combination with amino acids to enhance the natural flavorcharacteristics of tobacco, and especially the caramel-like or burnedsugarlike aroma thereof.

Japanese Pat. No. 9239/71 discloses certain tobacco "perfumes" such as1-deoxy-1-L-prolino-D-fructose, which is a sugar-amino acid condensationproduct. This compound, as well as others, are prepared by reacting anamino acid with a sugar in an aqueous or alcohol solvent, and usually inthe presence of an acid catalyst such as malonic acid. The desiredcompounds may be separated and purified by the use of ion-exchangeresins and are thereafter applied to tobacco.

Japanese Pat. No. 3398/73 discloses certain other specific aminoacid-sugars such as 1-deoxy-1-L-alanino-D-fructose that are synthesizedfrom their respective components by the Amadori rearrangement, in thepresence of malic acid as catalyst, by heating at 130° C. for 15minutes. The specific compounds are isolated and may be combined withcocoa to produce tobacco flavorants.

Two articles by Koehler (Journal of Agricultural Food Chemistry, Volume17, Number 2, pages 393-396, 1969 and ibid., Volume 18, Number 5, pages895-989, 1970) discuss pyrazine formation in sugar-amino acid modelsystems. The normal model system consists of asparagine and glucosereactants in a 1:1 molar ratio. Diethylene glycol solvent and a smallamount of water are also used as solvents. The mixture is heated for 24hours at 120° C. The use of a base catalyst, such as sodium hydroxide orammonium hydroxide, results in an increase in the production of volatilealkylated pyrazines. In some instances the addition of an aldehyde, suchas acetaldehyde, appeared to increase pyrazine formation. Koehler's workwas related to browning reactions known to occur in foods such asroasted peanuts, coffee, cocoa, and potato chips; and his primary objectwas to determine the chemical factors involved in volatile pyrazineformation during such reactions. Although volatile pyrazines wereisolated and identified, there is no suggestion by Koehler that hisreaction mixture would be suitable for use as a tobacco flavorant.

There is described in co-pending, commonly assigned U.S. applicationSer. No. 029,244 filed Apr. 12, 1979 certain reaction flavors forsmoking products wherein amino acids containing at least two nitrogensare reacted with reducing sugars and ammonium hydroxide in anessentially solvent-free system, and optionally in the presence ofcertain aldehydes. The ratio of reducing sugar to amino acids, based onweight, is in the range of about 2-8:1 and the ratio of sugar toammonium hydroxide is approximately 3-10:1 based on the weight of thereactants. The reactants are heated for a period of time sufficient toreach a temperature in the range of about 90° to 115° C. and thencooled. The resultant flavorant, either diluted or undiluted, is appliedto smoking compositions, and particularly reconstituted tobacco, at alevel between about 0.001 to about 5% based on the weight of thecomposition.

SUMMARY OF THE INVENTION

The present invention provides a method for preparing reaction flavorsfor smoking compositions wherein a reducing sugar is combined with asource of ammonia in the presence of a trace amount of an amino acid toform a reaction mixture which is heated to a temperature in the range ofabout 90° C. to 105° C. Once the desired temperature range is attained,the heating may be continued for about 5 to 15 minutes or, alternately,the reaction mixture is removed from the heat source and cooled to roomtemperature. The thus prepared mixture has been found to producedesirable reaction products highly suitable for use in smoking products,and particularly those having a high content of tobacco stems.Application of the reaction flavorant to the stems at a level up toabout 5% by weight of the stems produces an acceptable smoking product.

Although the reaction flavor product has been found particularlysuitable for use in enhancing the flavor and aroma of tobacco stems,such reaction flavors are equally suitable for use on other smokingmaterials selected from tobacco leaf, reconstituted tobacco, nontobaccosmoking substitutes and mixtures thereof. The reaction flavors may beincorporated therein at a level from about 0.5 to 10% by weight based onthe dry weight of the smoking material.

The use of such reaction flavors, particularly in tobacco compositionshaving a high stem content, results in a tobacco product having improvedsmoking characteristics. The flavorant-stem product is highly suitablefor use in cigarettes at a blend level up to 50% if desired.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reducing sugars are reacted with a source of ammonia in the presence ofa trace amount of certain amino acids to produce flavorants suitable foruse in smoking products. Suitable reducing sugars include glucose,fructose, mannose, galactose, and mixtures thereof, with syrupscontaining approximately 42% or more of fructose being preferred.Disaccharides and polysaccharides may also be used as the source ofreducing sugar as long as they are converted to monosaccharides byconventional hydrolysis prior to reacting with the other named reagents.Saccharide mixtures such as corn syrup, malt syrup and invert sugar mayalso be used as long as conversion to monosaccharides preceeds thereaction with amino acids.

Representative amino acids include aspartic acid and glutomic acid andthe monoamides thereof, specifically asparagine and glutamine. Theweight ratio of sugar to amino acid will generally be in the range of200-300:1 with a ratio of about 235-245:1 being preferred. The preferredsource of ammonia for purposes of this invention is concentratedammonium hydroxide. The weight ratio of sugar to concentrated ammoniumhydroxide (30%) will generally be about 5-15:1 with 6-8:1 beingpreferred. It will be appreciated that alternate sources of ammonia maybe employed, such as gaseous or liquid ammonia or subjectivelyacceptable ammonium salts. Suitable ammonium salts include ammoniumorthophosphate, ammonium dihydrogen orthophosphate, diammoniummonohydrogen orthophosphate, ammonium citrate, ammonium acetate and thelike.

The reaction is generally carried out in a flask, preferably oneequipped with a reflux condenser to prevent loss of desirable volatiles.The flask and contents may be heated in a steam bath, an oil bath, orthe like, and the time necessary to reach the optimum temperature ofabout 90° to about 105° C. is determined either by the size of thereaction vessel or the temperature of the heating system or both. Astainless steel jacketed vessel having a stem inlet and outlet,condenser and cooling coils may be used for larger scale reactions. Inmost instances it is only necessary to bring the reactants to thedesired temperature, and then the reaction is stopped by removing theheat source. In certain instances it may be desirable to continueheating for about 5 to 15 minutes once the desired temperature isattained. Best results are obtained when the reaction mixture isactively cooled to about 49° C. or lower. Cooling may readily beeffected by diluting the reaction mixture with water, or, alternatively,the reaction mixture may be cooled by means such as cooling coils withinthe reaction vessel, an ice bath and the like.

Although the cooled reaction flavor product may be used without furtherdilution, it may, in certain instances, be desirable to dilute theflavor product with an acceptable diluent. The degree to which thereaction flavor product is diluted with water or other acceptablediluent is a matter of choice and may, to some extent, depend upon itsultimate use. Generally a 1:1 to about a 5:1 dilution with water isadequate and results in an aqueous reaction flavorant product readilyadaptable for use on any type of smoking composition.

The term "smoking composition" includes all forms of tobacco, such asshredded filler, leaf, stem, stalk, homogenized leaf cured,reconstituted cigar binder, pipe tobaccos, or reconstituted tobacco insheet or predetermined forms, which are cast or extruded from "tobaccoslurries." Rolled and cut tobacco stems in either expanded or unexpandedform are particularly preferred. In addition, smoking compositions mayencompass the various smoking substitutes formulated from non-tobaccomaterials. The smoking substitute may be utilized alone or blended invarying proportions with other forms of tobacco. Representativeformulations for non-tobacco smoking materials may be found in U.S. Pat.Nos. 3,529,602; 3,703,177; 3,796,222; 4,019,521; 4,079,742; andreferences cited therein.

The reaction flavors produced in accordance with the present inventionmay be applied to the smoking composition by direct spraying methodsknown in the art. They may be applied by dispersing or diluting furtherin a suitable carrier, water for example, or may be directly mixed orotherwise combined with the smoking material. When an aqueous carrier isemployed, the mixture is air-dried or otherwise treated to remove thecarrier. Generally the reaction flavor product will be incorporated intothe smoking composition or a component thereof at a level of 0.5 to 10%by weight of the composition. It will be recognized that larger amountsof the reaction flavor product may be incorporated into a single tobaccocomponent which is then blended with other filler materials to produce asmoking composition having the previously described level of reactionflavor product.

The reaction flavors can, if desired, be incorporated in cigarette paperor in filters. However, it will generally be more desirable toincorporate the flavors in the smoking composition itself.

In a preferred embodiment, the cooled reaction flavor is dilutedapproximately 1:1 with water and sprayed or otherwise applied to rolled,crushed tobacco stems which are subsequently shredded and blended withconventional tobacco filler at a level up to about 50% based on thetotal weight of the filler. Humectants and additional casing materialsconventionally employed in tobacco processing may be incorporated withthe reaction flavorant or applied separately to the stem material. Stemshaving the reaction flavor applied thereto, on smoking, have a smootherresponse and less "stemmy" taste. In addition, stems containing thereaction flavor may be incorporated at a higher level in a blend thanpreviously possible.

the following examples are illustrative.

EXAMPLE 1

To a glass jacketed reaction vessel equipped with reflux condenser andstirrer/agitator were added the following reactants: 1278 grams of asyrup containing 72% fructose by weight (900 Isomerose TM Syrup, ClintonCorn Sweetners), 3.9 grams DL-aspartic acid and 150 ml of concentrated(30%) ammonium hydroxide. The contents of the reaction vessel werestirred and heated by passing steam through the jacket until thetemperature of the reaction solution reached 95° C. The steam wasterminated and the contents of the vessel were removed and allowed tocool to room temperature. The yield of reaction flavor product was1397.5 grams or 98.6%.

The cooled reaction mixture was sprayed on shredded, flue-cured tobaccostems to a level of 2.5% by weight. In addition, glycerine and propyleneglycol were sprayed to a level of 2% each by weight of the stems. Thestems were fabricted into cigarettes having conventional celluloseacetate filters attached thereto. Control cigarettes were made in asimilar manner using untreated stems. A small panel of experiencedsmokers smoked and compared the treated stem cigarettes with the controland found the treated cigarettes to be less hot and harsh. Although abitter aftertaste was noted, the treated cigarettes seemed smoother andless peppery than the control.

EXAMPLE II

In a manner similar to Example I, 314 grams Isosweet (Staley 71% solidssolution containing 42% fructose, 50% glucose, 1.5% maltose and 1.5%isomaltose) was combined in the glass jacketed reaction vessel with 1gram DL-aspartic acid and 37.6 grams concentrated ammonium hydroxide.Steam was passed through the jacket until the internal temperaturereached 94° C. The time required to reach the desired temperature was 15minutes. The final pH of the reaction mixture was 5.3.

The reaction mixture was cooled to room temperature and an aliquot ofundiluted reaction flavor product was sprayed on two batches offlue-cured tobacco stems to a level of 4% by weight and 2.6% by weightrespectively. Cigarettes were made using 100% of the treated stemmaterial. Controls were made using identical flue-cured stems having noreaction flavor added thereto. Cellulose acetate filters were attachedto all cigarettes prior to smoking. The cigarettes were smoked by anexperienced panel of smokers. The cigarettes having 4% reaction flavoradded thereto were found to have a burnt character or off-taste, wereslightly peppery, and had a hot aftertaste. The smokers also noted aslight papery character. The cigarettes treated at the 2.6% weight levelhad less stemmy character and hotness and were less papery than thecigarettes treated at the 4% level.

EXAMPLE III

The following ingredients were premixed and added to a reaction vesselcontaining 50 ml concentrated ammonium hydroxide as in Example I:

426 grams Isomerose 900;

1.3 grams glutamine.

The contents of the vessel were stirred and heated to 95° C. and thencooled. An aliquot of the cooled solution was diluted 1:1 with water and10 μl portions were injected into a conventionally blended cigarettecontaining 20% by weight of the blend of unflavored, uncasedreconstituted tobacco. The treated cigarettes were smoked and comparedto untreated controls containing the same blend. The treated cigaretteswere found to be generally smoother, less hot and peppery, less burntand slightly sweet. An off-note was noted.

Flue-cured stems were sprayed to a weight level of 2.5% with anundiluted aliquot of the reaction flavor. Propylene glycol and glycerinewere each sprayed on the same stems to a 2% weight level. On smoking,cigarettes containing the treated stems were found to have a smoother,slightly burnt and bitter taste as compared to the controls.

EXAMPLE IV

In a manner identical to Example III, 1.3 grams glutamic acid wassubstituted for glutamine and the mixture was heated to 95° C. andcooled. An aliquot of the reaction product was diluted 1:1 and 10 μlportions were injected into cigarettes identical to those of ExampleIII. On smoking, the treated cigarettes were found to be smoother, lessbitter, more peppery and salty. Flue-cured stems were treated as inExample III. On smoking, the treated stems were smoother, slightlysweet, had less burnt taste and were not as harsh. A slightly bitter tosweet aftertaste was noted by some of the smokers.

EXAMPLE V

Two reaction flavors (A and B) were prepared in which the reactants werecombined, heated to 93° C. in a reaction vessel and then cooled to roomtemperature. The reactants were as follows:

A. 361 grams 900 Isomerose TM; 1.3 L-glutamic acid; 50 ml concentratedNH₄ OH;

B. 542 gram 900 Isomerose TM; 1.3 L-glutamic acid; 50 ml concentratedNH₄ OH;

Undiluted reaction flavors A and B were sprayed on flue-cured brightstems to a level of 2.5% by weight of the stems. Glycerine andpolyethylene glycol were sprayed on the flavored stems at a 2% weightlevel. On smoking 100% stem cigarettes, a smoother, slightly greenpapery or burnt taste was noted for reaction flavor A. Cigarettescontaining reaction flavor B were slightly harsh, papery and had agreen, burnt taste.

What is claimed is:
 1. A process for preparing a reaction flavor productwhich comprises the following steps:(a) Preparing a mixture of areducing sugar .[.and.]. ammonium hydroxide .Iadd.and a trace amount ofa compound selected from the group consisting of an amino acid and amonoamide thereof, .Iaddend.wherein the weight ratio of reducing sugarto ammonium hydroxide (.Iadd.30%) .Iaddend.is in the range of 5-15:1.Iadd.and the ratio of reducing sugar to said compound is in the rangeof 200-300:1.Iaddend.; .[.(b) adding a trace amount of a compoundselected from the group consisting an amino acid and a monoamide thereofto said mixture of step (a), wherein the ratio of reducing sugar to saidcompound is in the range of 200-300:1;.]. .[.(c).]. (.Iadd.b).Iaddend.heating said mixture to a temperature in the range of 90° to105° C.; and thereafter .[.(d).]. (.Iadd.c) .Iaddend.cooling saidmixture to room temperature.
 2. The process of claim 1 wherein the saidcompound thereof is selected from the group consisting of aspartic acid,glutamic acid, asparagine and glutamine and their monoamides.
 3. Theprocess of claim 1 wherein the weight ratio of sugar to concentratedammonium hydroxide (30%) is 6-8:1.
 4. The process of claim 1 wherein thereducing sugar is selected from the group consisting of fructose,glucose, mannose, galactose and mixtures thereof.
 5. The process ofclaim 1 wherein the weight ratio of sugar to said compound is 235-245:1.6. The process of claim 1 wherein the reaction flavor product is cooledby diluting with water, said water being added in an amount sufficientto effect a 1-5:1 dilution of the reaction flavor product.
 7. Theprocess of claim 1 wherein heating is continued for 5 to 15 minutesafter the temperature reaches 90° to 105° C.
 8. A reaction flavorproduct prepared by the process of claim
 1. 9. A smoking compositioncomprising a filter material selected from tobacco, reconstitutedtobacco, non-tobacco smoking substitute and mixtures thereof, and thereaction flavor product of claim
 8. 10. The smoking composition of claim9 comprising a filler of blended tobaccos having incorporated thereinbetween about 0.5 to 10% by weight of the filler of the reaction flavorproduct.
 11. The smoking composition of claim 9 comprising a filler oftobacco, reconstituted tobacco and tobacco stems wherein tobacco stemscomprise up to 50% by weight of the filler and said stems haveincorporated therein up to 5% by weight of the stems of the reactionflavor product.
 12. The smoking composition of claim 9 comprising afiller of a non-tobacco smoking substitute having incorporated thereinbetween about 0.5 and 10% by weight of the smoking substitute of thereaction flavor product.